U.S. patent number 4,651,439 [Application Number 06/765,372] was granted by the patent office on 1987-03-24 for quill for coordinate measuring machines.
This patent grant is currently assigned to Mauser-Werke Oberndorf GmbH. Invention is credited to Gerhard Band, Gunter Berger, Kurt Walter.
United States Patent |
4,651,439 |
Band , et al. |
March 24, 1987 |
Quill for coordinate measuring machines
Abstract
The invention relates to a quill for coordinate measuring
machines of square cross-section and guided by a total of eight
bearing parts within a guiding part. Three bearing parts which bear
against quill surfaces are located adjacent the upper and in the
lower ends of the guide surfaces in the guiding part. Two more
bearing parts are provided in a Z direction approximately between
the upper and lower bearing parts. Due to the special configuration
of the bearing parts relative to each other and the horizontally
acting springs inserted in certain bearing parts the twisting of
the quill is determined and also the specified quill twisting
accuracy of two angular seconds max. is obtained.
Inventors: |
Band; Gerhard (Oberndorf,
DE), Berger; Gunter (Oberndorf, DE),
Walter; Kurt (Alpirsbach, DE) |
Assignee: |
Mauser-Werke Oberndorf GmbH
(DE)
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Family
ID: |
25823894 |
Appl.
No.: |
06/765,372 |
Filed: |
August 13, 1985 |
Foreign Application Priority Data
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Aug 16, 1984 [DE] |
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3430086 |
May 2, 1985 [DE] |
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3515685 |
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Current U.S.
Class: |
33/559; 33/503;
33/556 |
Current CPC
Class: |
G01B
21/04 (20130101); G01B 5/008 (20130101) |
Current International
Class: |
G01B
5/008 (20060101); G01B 21/02 (20060101); G01B
21/04 (20060101); G01B 005/00 () |
Field of
Search: |
;33/503,559,556,558,560,561,551,1M,169R,172R ;308/3A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3107783 |
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Sep 1982 |
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DE |
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2487931 |
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Feb 1982 |
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FR |
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Primary Examiner: Haroian; Harry N.
Attorney, Agent or Firm: McGlew and Tuttle
Claims
What is claimed is:
1. A quill construction for coordinate measuring machines,
comprising a guide having a bore, a quill of substantially
rectangular cross-section having means for accommodating a feeler
adjacent its lower end and guided in said bore for movement in a
Z-direction, said quill having a surface provided with a
Z-direction scale, said quill having two mutually perpendicular
first surfaces connected to each other at a first corner area, two
mutually perpendicular second surfaces connected to each other at a
second corner area which is diametrically opposite said first
corner area, said first surfaces being connected to said second
surfaces at two diametrically opposite third corner areas, said
surfaces extending in the Z-direction, said quill having upper,
intermediate and lower bearing zones spaced in the Z-direction, at
least two first bearings engaged between said guide and said quill
in each of said upper and lower zones, each of said at least two
first bearings engaged against one of said first surfaces, at least
oen second bearing engaged between said guide and said quill in
each of said upper and lower bearing zones and each engaged against
one of said second surfaces and second corner area for
counteracting forces of said first bearings in said upper and lower
bearing zones, and two intermediate bearings engaged between said
guide and said quill in said intermediate bearing zone, each
intermediate bearing engaged against one of said first surfaces
between said first bearings on each of said first surfaces and out
of vertical alignment with said first bearings on each of said
first surfaces, each of said first, intermediate and second
bearings slidably supporting said quill for movement in the
Z-direction on said guide.
2. A quill according to claim 1 wherein said first bearings in said
upper and lower zones are each adjacent said first corner area,
said intermediate bearings in said intermediate zone each being
adjacent one of said third corner areas.
3. A quill according to claim 2 wherein said second corner area is
flattened, said second bearing acting in said upper and lower
bearing zones against said flattened second corner area.
4. A quill according to claim 2 wherein said at least one second
bearing in said upper and lower bearing zones engages against one
of said second surfaces adjacent one of said third corner areas,
and additional second bearings in each of said upper and lower
bearing zones engaged against the other of said second surfaces
adjacent the other of said third corner areas, said intermediate
bearings each being acjacent one of said third corner areas.
5. A quill according to claim 1 wherein each of said intermediate
bearings adjacent one of said third corner areas.
6. A quill according to claim 1 wherein at least one of said first
bearings and at least one of said second bearings in spring loaded,
at least one of said intermediate bearings is spring loaded, all
other bearings being fixed to said guide.
7. A quill according to claim 1, wherein said bearings are located
at corner areas and one of said intermediate bearings are spring
loaded in a horizontal plane.
8. A quill according to claim 1, wherein said quill has a chamfer
on each of its corner areas.
9. A quill according to claim 1, wherein said surfaces of the quill
are chemically nickle-plated.
10. A quill according to claim 1, wherein said bearings include air
bearings.
11. A quill according to claim 1, wherein revolving ball shoes
guided on a hard surface of said quill are used as bearings.
Description
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a quill for coordinate machines of an
essentially rectangular, in particular squire cross-section, guided
in bearing parts so as to be movable in a Z direction and
accommodating a measuring feeler at its lower end.
Similar quills are disclosed in German No. OS 31 07 783 in the
introductory description thereof. In order to reduce the weight of
such quills it has been suggested in German No. OS 31 07 783 to
depart from the square section of the quill and produce a quill of
triangular section instead. In comparison with the square, and also
in comparison with the generally known circular cylinder form, a
triangular section presents less surface, whereby a corresponding
weight reduction is achieved.
The new VDI acceptance guidelines for three coordinate measuring
instruments provide a test for quills, allowing a maximum of two
angular seconds for the twist angle or roll angle accuracy. This
extraordinarily high accuracy is not attainable in the known quill
designs with triangular or round section, or is attainable only at
extremely high expense for assembly and adjustment. Maintaining the
specified accuracy is problematical especially if, in large
measuring machines, the quill is to be extended in the Z direction
over a long distance of, say, two meters or more.
SUMMARY OF THE INVENTION
The invention provides a quill for coordinate measuring machines
which makes an accuracy for the twist angle of less than two
angular seconds possible by relatively simple means and also in
mass production.
According to the invention, the quill is equipped with a Z scale
and is guided in at least eight bearing portions in a guiding part,
of which, at least three bearing parts each are disposed in both
the upper and lower end zones of the guiding part in one
cross-sectional plane and mutually parallel in a Z direction, while
two more bearing parts are provided approximately in the middle
between the bearing parts spaced in the Z direction, in a
cross-sectional plane and offset in the Z direction relative to the
upper and lower bearing parts. Two each of the upper and lower
bearing parts are disposed catti-corner on the surfaces adjacent to
each other at right angles, while the third bearing part in the
same cross-sectional plane is provided at the diagonally opposite
corner, forming a V with the first two bearing parts, and the
bearing parts installed approximately in the middle between the
upper and lower bearing parts in the Z direction are provided on
the same guide surface as the two first mentioned upper and lower
bearing parts, but in the area associated with the respectively
opposite corner.
In an ornamental and structurally different embodiment, four each
bearing parts may be provided on each of the four guide surfaces in
both the upper and lower end zones of the quill, while in the
central quill zone two more bearing parts, offset by 90.degree. on
the respective guide surfaces, are installed additionally in a Z
direction between the upper and lower bearing parts.
In an embodiment of the invention, the bearing parts provided
catti-corner and centrally may be installed at or near the outside
edges of the guide surfaces. Furthermore, the two bearing parts in
the corner and one of the centrally disposed bearing parts may be
spring loaded in the horizontal plane.
In yet another embodiment, the quill is chamfered at its four
corners. To ensure perfect guidance and prevent twisting of the
quill, a spring loaded bearing part each may be installed opposite
the upper and lower fixed bearings, while a sprung bearing part,
offset by 90.degree., is coordinated with the central bearing.
The prevent corrosion when air bearings are used, the guide
surfaces are chemically nickleplated. If the bearings are designed
as revolving ball shoes instead, the guide surfaces of the quill
will be hardened in a further development of the invention.
With these inventive features safe adherence to and attainment of
the desired maximum quill twist are assured through a larger
guidance base of the square quill shape and the appropriate
arrangement of the guide elements. The employment of revolving ball
shoes or air bearings advantageously prevents the quill from
heating up. With the three point bearing in one cross-sectional
plane precise guidance of the quill is obtained. The reliable
determination of the quill rotation is obtained, for instance, by
one revolving ball shoe being fixed and the other revolving ball
shoe in the respective horizontal plane being sprung. Due to the
installation of the bearing parts near the edge of the guide
surfaces a broad bearing surface and, hence, increased accuracy are
obtained. The use of the springs allows, through spring layering or
the employment of special springs, to make the contact pressure of
the bearings against the quill available. If air bearings are used
instead of the revolving ball shoes, a weight reduction is possible
in addition.
A commercially available square tube is advantageously started with
outsides which are machined by chip removal, thereby arriving at
the required outside size for insertion of the quill into the
quidance parts. For this purpose the four corners of the quill body
are chamfered. Usually, this chamfer is insufficient to accommodate
a bearing part and thereby obtain in simple manner a three-point
bearing in one single cross-sectional plane.
It is only through the feature according to the invention, namely
to mount in both the upper and lower quill zones four each bearing
parts on the four lateral guide surfaces and, additionally, to
provide opposite each fixed bearing a spring loaded bearing part,
that adequate guidance of the quill is achieved. This design
according to the invention allows further the use of commercially
square tubing, whereby the technical cost of producing a special
quill is significantly reduced. Due to the centrally disposed
bearing parts mutually standing at right angles, good protection
against quill twisting with precisely defined quill guidance is
achieved.
Accordingly, it is an object of the invention to provide an
improved guidance for a measuring quill which is adapted to have a
measuring feeler and which is guided in a guiding part on bearings
arranged at three separate longitudinally spaced apart zones
including an upper zone having bearings which are at right angles
to each other adjacent one corner of the quill and at least one of
which is spring loaded with bearing means at an opposite corner
which is also spring loaded and both the upper and lower ends of
the quill and additional bearing means intermediate the upper and
lower ends which act adjacent to diametrically opposite corners
which are not the same of the corners as the upper and lower ends
and which includes spring loaded bearings on at least one of these
corners.
A further object of the invention is to provide quill for
cooridinate measuring machines which is simple in design, rugged in
construction and economical to manufacture.
The various features of novelty which characterize the invention
are pointed out with particularity in the claims annexed to and
forming a part of this disclosure. For a better understanding of
the invention, its operating advantages and specific objects
attained by its uses, reference is made to the accompanying
drawings and descriptive matter in which preferred embodiments of
the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a side elevational view of a quill partly in longitudinal
section constructed in accordance with the invention;
FIG. 2 is a top view of the quill of FIG. 1;
FIG. 3 is a side elevational view partly in section of the quill
according to the invention when used in a measuring machine;
FIG. 4 is a partial sectional and elevational view of another
embodiment of a quill; and
FIG. 5 is a partial horizontal sectional and top view of the quill
shown in FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings in particular, the invention embodied
therein comprises a quill generally designated 1 for coordinate
measuring machines which is adapted to contain a measuring feeler 4
at its lower end and which is guided in a guiding part 2 on
bearings which are located at three spaced apart bearing zones. The
bearing zones include an upper bearing zone in which two first
bearings 13 and 14 act at right angles to each other adjacent a
first corner area 16 between first side surfaces 10 and 11 of the
quill 1. Second bearings comprise bearings 15 biased by springs 18
against a flattened second corner area 17 so that they are diagonal
to the corner 16.
A lower bearing zone is provided with bearings similar to the first
bearing in an arrangement similar to the upper bearing zone.
The arrangement also includes an intermediate bearing zone in which
there are intermediate bearings 19 and 20 which operate adjacent
corners 21 and 22 which are diagonally opposite to each other and
which are not the same corners as in the upper and lower zones and
which act on surfaces 10 and 11 at right angles to each other.
Quill 1 which also includes surfaces 8 and 9 which are opposite the
surfaces 10 and 11 respectively and the surface 9 is advantageously
provided with a Z scale.
In the embodiment of FIGS. 4 and 5, the upper bearing zone includes
first bearings 28,29 which act at one end of a first surface 24 and
25 and second bearings, 31 which acts at an opposite second
surfaces 23, 26 in a corner area adjacent the surfaces 24, 25 and
they are advantageously spring biased. In the intermediate zone
intermediate bearings 32 and 33 act on surfaces 25 and 24 at
diagonally opposite corners and one of them, 32, is advantageously
spring biased.
A quill 1 is guided in a guiding part 2 of a coordinate measuring
machine. Fastened to the lower face end of the quill is a measuring
feeler 4. The quill 1 is movable in a Z direction by a drive
located at the upper end and not detailed here. The motion of the
measuring feeler 4 in Y direction is accomplished by a built-in
carriage 6 while mobility in X direction occurs through the entire
portal 7 of the measuring machine 3.
Now, in accordance with its square cross-section, the quill 1 has
four side surfaces 8,9,10,11 which at the same time represent guide
surfaces. The Z scale 12 is provided on the one side surface 9.
The bearing parts are shown schematically. In both the upper and
lower end zones of the guiding part 2 the bearing parts 13, 14, 15
designed in the form of revolving ball shoes as three point
bearings, are shown in one cross-sectional plane each. The bearing
parts 13 and 14 are disposed catti-corner on respective guide
surfaces 10 and 11 adjacent to each other and at right angles of
corner 16, both in the upper and lower end zones of the guiding
part 2. Diagonally opposite the corner 16 of the quill 1, at the
flattened corner 17, another bearing part 15 is disposed at the
same level as the bearing parts 13 and 14. This bearing part 15 in
both the upper and lower end zones of the guiding part has
horizontally acting springs 18.
In a Z direction shown by the double arrow 5, approximately in the
middle between the upper and lower bearing parts 13,14,15 are two
more bearing parts 19 and 20. The bearing part 19 is active on the
same guide surface 11 as the bearing part 14. But it contacts the
edge or corner 21 of quill 1 opposite the bearing part 14. Like the
bearing part 15, the bearing part 19 is supported by a horizontally
acting spring 18. The bearing part 20 is located on the guide
surface 10 which also accommodates the bearing part 13. Here again,
the bearing part 20 is disposed adjacent the edge or corner 22 of
the quill opposite the bearing part 13.
A total of eight guiding elements is provided in the above
described arrangement of the bearing parts 13, 14, 15, 19, 20. In
each of the upper and lower end zones of the guiding part 2 are
located three bearing parts 13,14,15, of which the bearing parts 15
disposed at the flattened corner 17 are spring loaded. The two
other bearing parts 19 and 20 are located in the center of the
perpendicular of the guide plane, one of which, namely bearing part
19, again being supported by a spring 18. The three point bearing
thus obtained for each upper and lower guide surface assures great
guiding accuracy. The quill twisting is determined by the bearing
parts 19 and 20, one of which is rigid and the other sprung. The
contact pressures of the bearing parts against the guide surfaces
of the quill 1 are controllable through the inserted springs
18.
If a weight reduction is desired, the revolving ball shoes used may
be replaced by air bearings as bearing parts.
FIGS. 4 and 5 show an alternate embodiment of the invention, the
differences relative to FIGS. 1 and 2 being essentially in the
number and arrangement of the bearing parts. According to FIGS. 4
and 5 also, a quill 1 is guided in a guiding part 2 of a coordinate
measuring machine 3 (not detailed). Again, a measuring feeler, (not
detailed) is fastened to the lower face end of the quill 1. The
quill 1 can move in the Z direction. The movements of the measuring
feeler in Y direction are accomplished via a built-in carriage
while the mobility in the X directions occurs through the entire
portal of the measuring machine.
Now, in accordance with its square cross-section, the quill 1 has
four lateral guide surface 23, 24, 25, 26. The Z scale 27 is
mounted to the one guide surface.
In both the upper and lower end zones of the quill 1 or the guiding
part 2 are provided the bearing parts 28, 29,30, 31, 32, 33,
designed as air bearings, as three point bearings in one
cross-sectional plane each. There is a total of four bearing parts
28, 29, 30, 31 on the four lateral guide surfaces 23, 24, 25, 26 of
the quill 1 in each of the upper as well as lower end zones of the
guiding part 2. Coordinated with each fixed bearing 28, 29 there is
a spring loaded bearing part 30, 31. The fixed bearings 28 and 29
are always disposed opposite the spring loaded bearing parts 30 and
31 on the side surfaces of the quill 1. This arrangement of four
bearing parts 28, 29, 30, 31 each in the upper and lower area of
the guiding part 2 replaces the catticorner arrangement of bearing
parts.
When, however, a commercially available square tube is used to
produce the quill 1 whose outside, for instance, must be machined
by chip removal to be able to insert it in the guiding part 2, the
chamfers 34 provided at the four corners of this quill body 1 are
insufficient to accommodate a bearing part. If the technically and
economically favorable solution of commercial square tubing is to
be utilized just the same, the invention still provides the
possibility of precise guidance of the quill 1 in the guiding part
2 and good protection against twisting of the quill 1 despite the
elimination of catti-corner bearing parts. Responsible for this
antitwisting protection of the quill 1 are essentially the two
central bearing parts 32 and 33 disposed on two guide surfaces 24
and 25 of the quill 1 which stand at right angles to each other.
Here again, one bearing part 33 forms a rigid bearing while the
other bearing part, offset to the former by 90.degree., again
represents a spring loaded bearing part 32.
To prevent corrosion in case the bearing parts are designed as air
bearings, the guide surfaces 23, 24, 25, 26 of the quill 1 are
chemically nickleplated.
In the event the bearing parts 28, 29, 30, 31, 32, 33 are revolving
ball shoes, the guide surfaces 23, 24, 25, 26 of the quill 1 are
hardened.
While specific embodiments of the invention have been shown and
described in detail to illustrate the application of the principles
of the invention, it will be understood that the invention may be
embodied otherwise without departing from such principles.
* * * * *